I've been encouraged by my employer to recalculate my W4 allowances in light of the tax law changes for 2018.
When I use the IRS's calculator it needs me to give answers for things like, Enter your total 2018 contribution for...
I'd like to update my W4 now if there's any advantage to be had, but I'm not sure how to come up with these values. Should I use the value to date? Project into the future assuming nothing changes? Guesstimate? Wait until next year?